US2021215855A1PendingUtilityA1
Nanoimprinted microlens array and method of manufacture thereof
Est. expiryJan 13, 2040(~13.5 yrs left)· nominal 20-yr term from priority
G02B 5/1885G02B 5/1809G02B 3/08G02B 3/0056G02B 3/0037G02B 3/0031
45
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Claims
Abstract
A microlens array may be formed by nanoimprint lithography. Each microlens of the array comprises a plurality of concentric ridges extending from the substrate and separated by concentric grooves. A ratio F of a width of the concentric ridges to a pitch p of the concentric ridges is a function of a radial distance r from a microlens center to the concentric ridges. An effective refractive index n of microlenses depends on a fill ratio of a binary pattern, which depends on the radial distance from the microlens center. A method of manufacturing a microlens array includes forming an imprint resist layer on a substrate, and imprinting the imprint resist layer with a mold having an inversed microlens nanostructure.
Claims
exact text as granted — not AI-modifiedWhat is claimed is:
1 . A microlens array component comprising:
a substrate; and an array of microlenses formed on the substrate by nanoimprint lithography; wherein each microlens of the array of microlenses comprises a plurality of concentric ridges extending from the substrate and separated by concentric grooves, wherein a ratio F of a width of the concentric ridges to a pitch p of the concentric ridges is a function of a radial distance r from a microlens center to the concentric ridges.
2 . The microlens array component of claim 1 , further comprising an imprint resist layer supported by the substrate, wherein the array of microlenses is formed in the imprint resist layer.
3 . The microlens array component of claim 1 , wherein the concentric grooves comprise air.
4 . The microlens array component of claim 1 , wherein the plurality of concentric ridges comprises circular ridges having a rectangular or trapezoidal cross-section.
5 . The microlens array component of claim 1 , wherein the concentric ridges of the plurality of concentric ridges have a substantially same height.
6 . The microlens array component of claim 5 , wherein the substrate is flat.
7 . The microlens array component of claim 1 , wherein an effective refractive index n of each microlens of the array of microlenses is a function of the radial distance r
n ( r )= n R F ( r )+ n G (1− F ( r )),
wherein n R is a refractive index of the concentric ridges, and n G is refractive index of the concentric grooves.
8 . The microlens array component of claim 7 , wherein each microlens has a phase profile comprising a plurality of concentric phase profile segments having an amplitude of 2π and adding up to a parabolic phase profile.
9 . The microlens array component of claim 7 , wherein each microlens has a phase profile
ϕ
′
(
r
)
=
[
2
π
λ
(
f
2
+
r
2
-
f
)
-
ϕ
(
0
)
]
mod
2
π
wherein f is a focal length of the microlens, λ is wavelength of impinging light, and ϕ(0) is a phase at the microlens center.
10 . The microlens array component of claim 1 , wherein a height of the concentric ridges is less than 1700 nm.
11 . The microlens array component of claim 1 , wherein the pitch p of the concentric ridges is less than 600 nm.
12 . The microlens array component of claim 1 , wherein each microlens of the array of microlenses is no greater than 0.1 mm.
13 . A mold for manufacturing a microlens array component, the mold comprising an array of inverted microlenses, wherein each inverted microlens of the array of inverted microlenses comprises concentric mold ridges extending from the mold and separated by concentric mold grooves, wherein a ratio F′ of a width of the concentric mold grooves to a pitch p′ of the concentric mold grooves is a function of a radial distance r′ from the inverted microlens center to the concentric mold grooves.
14 . The mold of claim 13 , wherein the concentric mold ridges have a substantially same height.
15 . A method of manufacturing a microlens array component, the method comprising:
forming an imprint resist layer on a substrate; obtaining a mold comprising an array of inverted microlenses, wherein each inverted microlens of the array of inverted microlenses comprises concentric mold ridges extending from the mold and separated by concentric mold grooves, wherein a ratio F′ of a width of the concentric mold grooves to a pitch p′ of the concentric mold grooves is a function of a radial distance r′ from an inverted microlens center to the concentric mold grooves; and imprinting the imprint resist layer with the mold so as to form an array of microlenses in the imprint resist layer; wherein each microlens of the array of microlenses comprises a plurality of concentric imprint ridges extending from the substrate and separated by concentric imprint grooves, wherein a ratio F of a width of the concentric imprint ridges to a pitch p of the concentric imprint ridges is a function of a radial distance r from the microlens center to the concentric imprint ridges; and wherein F′(r′)=F(r) at r′=r.
16 . The method of claim 15 , wherein an effective refractive index n of each microlens of the array of microlenses is a function of the radial distance r
n ( r )= n R F ( r )+ n G (1− F ( r )),
wherein n R is a refractive index of the concentric ridges, and n G is refractive index of the concentric grooves.
17 . The method of claim 16 , wherein each microlens has a phase profile comprising a plurality of concentric phase profile segments having an amplitude of 2π and adding up to a parabolic profile.
18 . The method of claim 16 , wherein each microlens has a phase profile
ϕ
′
(
r
)
=
[
2
π
λ
(
f
2
+
r
2
-
f
)
-
ϕ
(
0
)
]
mod
2
π
wherein f is a focal length of the microlens, λ is wavelength of impinging light, and ϕ(0) is a phase at the microlens center.
19 . The method of claim 15 , wherein the plurality of concentric imprint ridges comprises circular imprint ridges.
20 . The method of claim 15 , further comprising reactive ion etching the imprint resist layer after imprinting with the mold.Join the waitlist — get patent alerts
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